It is a little difficult to fathom that the sun is also layered, that too with seven different layers! But yes, this gigantic ball of gases burning at millions of degrees has several layers and it is the radiation of only the topmost layer that is visible to us.
Each of the seven layers of the sun has its own characteristics and functions. As the sun is a very important part of our solar system, without it neither the life on Earth nor the orbit of other planets and celestial bodies in our solar system would sustain. Therefore it is essential to understand the sun and its composition.
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What is the Sun?
The sun is a star and one of the main celestial bodies in our solar system. It is the largest and heaviest celestial body in our solar system around which the various planets, comets, meteors and other celestial objects revolve.
It is the gravity of the sun that pulls the planets together and the energy of the sun that makes life possible on Earth. Thus, this body of 4 trillion pounds which is around 93 million miles (150 million kilometers) away from our planet is the source of life.
Layers of the Sun
In all, there are seven layers of the sun. Out of these three are inner layers and four are outer layers. The energy is generated by the sun in its inner layers which is reflected in the outer layers. The sun has an outer atmosphere that acts as an envelope for the corona.
These layers are so complicated in features that they have massive temperature variations ranging from 5780K in router layers to 15 million K near the core. Let’s explore each of these layers in detail.
The Core is the innermost layer with the highest temperatures and a site for all thermonuclear processes. Hydrogen is converted into Helium in these layers.
Feature: Fusion of hydrogen atoms to form Helium
Colour: Pink glow (Colour of hydrogen plasma)
Temperature: 15 Million K
It is also a part of the inner layers of the sun and covers nearly 70% of the sun’s radius. Photons travel in this layer to carry energy generated in the core outwards in the form of radiation. It takes photons millions of years to carry radiation.
Feature: Carry radiations
Temperature: 2 Million K
The Convection Zone expands upto 200,000 kilometres and is the last and outermost layer of the inner layers of the sun. Due to the heating and cooling of particles, there are convection currents generated in this layer that carry the radiation further to the outer layers. This layer works just like water boiling in a pan.
Feature: Carry photons via convection currents
Temperature: 5700 K
The lowest outer layer of the sun that is visible to us is the Photosphere. The photon radiations enter the photosphere and the sun spots created by magnetic fields cause the major activities in this region. Granulation also happens in the photosphere and the temperature here fluctuates heavily.
Feature: Granulation due to the convection layer.
Colour: White or Yellow
Temperature: 6500 K (bottom) to 4000 K (top)
The temperature of the sun rises with distance in this layer. It causes the hydrogen atoms to release a reddish light. Rising jets of gas called spicules carry radiation upwards at the speed of 30 km/hr in this layer.
Feature: Generates short-lived spicules (life 10 min) to carry energy
Temperature: 4000 K (bottom) to 8000 K (top)
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A thin 60-mile wide layer between the chromosphere and the corona. A rapid temperature increase takes place in this layer of the sun.
Feature: Rapid rise in temperature
Temperature: 8,000 to 500,000 K
The outermost and visible layer of the sun is called the Corona. It can be seen during the solar eclipse as a whitish halo or a disk. It forms the solar holes from which the solar wind emerges. The wind contains particles of the sun and appears as an extension of the corona making its definite shape undefined.
Feature: Strong magnetic fields act here to bind the plasma and prevent the escape of solar wind.
Temperature: 500,000 to 2,000,000 K.
Structure of the Sun
From a distance as great as that between the Earth and the Sun, the sun appears like a uniform and solid sphere. Contrastingly, the sun’s surface, which is made up of various gases is highly variable. It has a core and complex reactions taking place throughout its layers and gases and solar storms emanate from its surface layer. Most of the mass of the sun exists in the form of a fourth state of matter called plasma. It is a superheated gas with a positive electrical charge and is constantly reacting.
Diagram of the Layers of the Sun
Here is a diagram depicting the layers of the sun.